US3671156A - Press forming machine - Google Patents

Abstract

A MACHINE AND METHOD OF PRESS FORMING AN INITIALLY FLOCCULENT CEMENTITIOUS MIXTURE TO PRODUCE A RECTANGULAR, ROUND OR OTHER SHAPED OPEN BOXLIKE PRODUCE SUCH AS A METER HOUSING, THE MACHINE INCLUDING A CORE MOUNTED BETWEEN GUIDE WALLS IN ANGULAR RELATION THEREWITH, A PAIR OF OPPOSED HORIZONTALLY MOVABLE PRESSURE DIES HAVING ANGULARLY RELATED SURFACES PARALLEL TO CORRESPONDING SIDES OF THE CORE AND SLIDABLE BETWEEN THE GUIDE WALLS TO COMPRESS THE MIXTURE AGAINST THE CORE, AND A VERTICALLY MOVABLE PRESSER DIE RING SLIDABLE BETWEEN THE CORE AND THE OPPOSED PRESSER DIES TO EFFECT A SUPPLEMENTARY VERTICAL PRESSING OF THE MIXTURE AND TO SHAPE THE TOP PORTION OF THE PRODUCT, THE METHOD INVOLVING THE INITIAL PRESSING OF A PORTION OF THE PRODUCT TO A PREDETERMINED DENSITY, AND THE REMAINDER TO A PREDETERMINED LESSER DENSITY, THEN PRESSING THE REMAINDER IN A VERTICAL DIRECTION TO ESSENTIALLY THE SAME DENSITY.

Description

June 20, 1972 J. 1.. ROBBINS 3,671,156

PRESS FORMING MACHINE Filed Se t. 4, 1970 4 Sheets-Sheet 1 2 2 ,LI i

INVENTOR.

c/AMEs L BOBB/MS A 770 Eva 5 June 20, 1972 J. L. ROBBINS PRESS FORMING MACHINE 4 Sheets-Sheet 2 Filed Sept. 4, 1970 I j/ INVENTOR. JAMES LEOBB/NS ATTOEA/E S Jun 20, 1972 J, ROBBINS 3,671,156"

' PRESS FORMING MACHINE Filed Sept. 4, 1970 4 Sheets-Sheet 3 0 i Q INVENTOR. 1 U -13; g c/AMES LEoaa/A/s L L w BY m aw June 20, 1972 J. L. ROBBINS 3,671,156

PRESS FORMING MACHINE Filed Sept. 4, 1970 4 Sheets-Sheet 4.

FIG. /4

. INVENTOR. c/AMES L. Boas N5 United States Patent 3,671,156 PRESS FORMING MACHINE James L. Robbins, West Covina, Calif., assignor to Brooks Products, Inc., El Monte, Calif. Filed Sept. 4, 1970, Ser. No. 69,797 Int. Cl. B29c 1/00 US. Cl. 425-130 Claims ABSTRACT OF THE DISCLOSURE A machine and method of press forming an initially flocculent cementitious mixture to produce a rectangular, round or other shaped open boxlike product such as a meter housing, the machine including a core mounted between guide walls in angular relation therewith, a pair of opposed horizontally movable presser dies having angularly related surfaces parallel to corresponding sides of the core and slidable between the guide walls to compress the mixture against the core, and a vertically movable presser die ring slidable between the core and the opposed presser dies to effect a supplementary vertical pressing of the mixture and to shape the top portion of the product; the method involving the initial pressing of a portion of the product to a predetermined density, and the remainder to a predetermined lesser density, then pressing the remainder in a vertical direction to essentially the same density.

BACKGROUND OF THE INVENTION It has been the custom for many years to cast open end, rectangular, round or other shaped meter boxes or housings out of concrete. Such products have low structural strength and are heavy so that damage to the boxes can be substantial, especially during handling, transportation and installation.

SUMMARY OF THE INVENTION The present invention is directed to a machine and method of press forming which is particularly adapted, but not limited to, the production of meter boxes or housings of rectangular shape, open top and bottom, and intended to be set flush in the ground. The invention is summarized in the following objects:

First, to provide a machine and method which is particularly suited for the compressing of a type of mixture disclosed in Pat. No. 3,204,019, while shaping the mixture into the desired configuration; however, the machine and method is adapted for the forming of cementitious mixtures generally.

Second, to provide a machine and method, as indicated in the other objects, whereby the compressible mixture is first compressed transversely about a central core, then compressed axially to form a dense mass capable of being removed intact from the press and cured, thereby to produce a product which is not only lighter than concrete, but also much stronger so as to withstand more readily the loads imposed incidental to transportation, installation and ultimate use.

Third, to provide a machine and method, as indicated in the other objects, wherein the product may be constructed with thicker walls in, for example, its upper or rim portion yet the mixture is compressed substantially uniformly throughout its mass.

Fourth, to provide a machine and method, as indicated in the other objects, wherein a rectangular core is secured between guide walls with two corners in confronting relation therewith, a pair of horizontally movable pressing dies having V-shaped operating faces are simultaneously movable toward the core to compress an initially loose mass of cementitious mixture, whereupon a vertical die Patented June 20, 1972 DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of the machine for press forming a cementitious mixture.

FIG. 2 is a sectional view thereof, taken through 2P4 of FIG. 1, showing the pressing dies in a retracted position.

FIG. 3 is an enlarged view, taken within Circle 3 of FIG. 2, showing the pressing dies in their extended position upon completion of the pressing operation, and indicating fragmentarily in plan a completed product, portions of one die and the supporting pallet being broken away to indicate underlying structure.

FIG. 4 is a further enlarged fragmentary plan view, taken within Circle '4 of FIG. 3, showing one corner of the core and adjacent portions of the pressing dies, the dies being in their extended position.

FIG. 5 is a similar fragmentary plan view, showing the dies partially retracted and in the position assumed when introducing a cementitious mixture.

FIG. 6 is a fragmentary sectional view at a reduced scale, taken through 66 of FIG. 5, showing confronting portions of the core and presser die in position for receiving a cementitious mixture therebetween.

FIG. 7 is a similar view, taken through 7-7 of FIG. 4, showing the presser die as it appears on completion of the pressing operation.

FIG. 8 is a similar fragmentary sectional view, showing the presser ring inserted between the core and presser die to complete the forming operation.

FIG. 9 is a fragmentary sectional view, at a reduced scale, taken through 99 of FIG. 5, showing the confronting portions of the core and presser die in position for receiving a cementitious mixture.

FIG. 10 is a similar fragmentary sectional view, taken through 10-10 of FIG. 4, showing the core and presser die on completion of the pressing operation.

FIG. 11 is a similar sectional view, showing the vertical presser ring after completion of its operation.

FIG. 12 is a fragmentary sectional view of the core and a presser die, shown in their separated position with uncompacted cementitious material therebetween and showing a web forming die, incorporated in the presser die.

FIG. 13 is an enlarged fragmentary sectional view, taken within Circle 13 of FIG. 12, showing the web forming die in its web forming position.

FIG. 14 is a fragmentary sectional view, showing a modified embodiment of the web forming die.

SPECIFICATION The machine and method for press forming is particularly adapted to the forming of a cementitious mixture, which is initially in a loose flocculent state and capable of compression to a third or a half of its initial volume. An example of a mixture suitable to the purposes of the present invention is the mixture described in Pat. No. 3,204,019, issued Aug. 31, 1965. s

The machine and method is primarily intended to form meter boxes or housings which are rectangular in plan and open at their top and bottom ends. However, the machine and method may be adapted to form round structures or structures of other shapes. More particularly, the meter box 1 illustrated has a lower portion 2 having relatively thin uniform walls, except for the taper needed to remove the meter box from the machine, and a relatively thick upper portion 3 which is provided with an internal shoulder 4 to support a cover. Also, externally,

the end walls may be straight with an internal offset 5; whereas, the side walls may be offset externally, as indicated by 6, and internally as indicated by 7. Finally, the corners of the upper portion are rounded internally as well as externally; whereas, externally the lower portions of the meter box may be beveled at the corners, as indicated by 8.

The external offset 16, which may include the ends as well as the sides, accomplishes two purposes. (1) The meter box is stronger so as to better resist rough treatment during handling, shipping and installation. (2) The shoulders formed by the offset provide a means of keeping the meter box at grade level.

The machine includes a vertical frame structure 9 which supports a horizontal frame structure 10. The horizontal frame structure 10 includes a bottom plate 11, side walls 12, end walls 13 and a top plate 14, forming a boxlike structure. At their midportions, the side walls 12 are lined with relatively thick plates which form guide walls 15.

The bottom plate 11 is provided with a central opening 16 extending between the guide walls 15. The opening 16 is essentially rectangular with its sides disposed at a forty-five degree angle to the longitudinal axis of the frame structure 10. Underlying the opening 16 is a core supporting grid 17, comprising longitudinal bars. Supported on the grid 17 is a core mounting plate 18 on which is secured a rectangular core 19. The core tapers upwardly and is provided with rounded corners 20. Also, the core tapers upwardly to permit withdrawal of the finished product and extends higher than the finished product. The core is positioned with its side walls defining forty-five degree angles with the guide walls 15. The top wall has a clearance opening 21.

The horizontal frame structure 10 receives a pair of opposed horizontal pressing dies 23, which include die surfaces '24 and 25 confronting the core 19, and disposed at a forty-five degree angle to the guide walls 15. The upper portions of the die surfaces are joined by a curved surface 26, whereas, their lower portions are joined by beveled surfaces 27. The lateral extremities of the die surfaces taper to relatively sharp edges and terminate in beveling extensions 28. In the region corresponding to the cured die surfaces 26, the guide walls are provided with curved recesses 29, complementary to the upper portions of the die surfaces 24 and 25.

Each pressing die 23 is moved horizontally by a hydraulic unit 30, the base of which is attached to a corresponding end wall 13'.

The vertical frame structure 9 extends above the horizontal frame structure 10' and guides a vertical pressing die 31, having a downwardly extending internal rim 32. The pressing die 31 is operated by a hydraulic unit 33, carried by the vertical frame structure.

A pallet frame 34 is removably mounted on the grid 17 and surrounds the core mounting plate 18, which has the same dimensions as the base of the core 19. The pallet frame includes beveled portions 35 so that the pressing die may move partially over the pallet frame in the course of forming the product. When the pallet frame is removed, the grid 17 permits excess mixture to be cleaned from the core and die surfaces and removed.

Mounted at the bottom of the frame structure 10 is a hydraulic unit 36 which supports a mounting plate 37, from which extend upwardly directed ejector rods 38, positioned to engage the pallet frame 34 so that when the product is completed, it may be raised for removal as indicated in FIG. 1.

The method of press forming a cementitious mixture to produce, as indicated, an open end boxlike product is as follows:

The vertical pressing die 31 is disposed in its upper position initially and the horizontal pressing dies are retracted from the core a predetermined distance. The spacing between the core and the bottom plate 11 is such as to receive the pallet frame with the pallet frame supported on the grid 17. The initial spacing, particularly in regard to the lower portions of the core and horizontal pressing dies is predetermined so that when the pressing dies move totheir final position relative to the core, all of the mixture therebetween will be compressed a predetermined amount.

The cementitious mixture is prepared with an appropriate amount of water so that the mixture is in a flocculent state. A predetermined amount of the mixture is placed between the core and the horizontal dies, preferably this space is equal to the desired quantity of the mixture, and appears as indicated by '39 in FIGS. 6 and 9.

The mixture is compresed by movement of the pressing dies 23 a predetermined distance toward the core. The walls of the lower portion of the product, including the corners thereof, have essentially uniform thickness. Furthermore, by reason of the fact that the sides of the core and the corresponding die surfaces 24 and 25 are placed at forty-five degree angle to the axis of travel, or nearly so, uniform compression of the mixture is attained. This is also essentially true of the material in the region of the bevel surfaces 27. Still further, it is also true of the portions of the mixture which form the lateral lower corners of the product. Any variation in density is so slight as to be negligible. By way of contrast, this would not be so if the core were cylindrical and the die surfaces were semi-cylindrical. In such case, the density decreases laterally and to an increasing degree until at the lateral sides the density is a half or a third that attained at the central portion. Thus, should a cylindrical shape be desired, a set of four radially movable dies is used to maintain a more uniform density.

The upper portion of the product by reason of the greater distance between the core and the die is initially compresed to a lesser extent. After the horizontal dies have completed their operation, the vertical die is moved downwardly between the core and the die surfaces to compress the upper portion vertically until it too attains the same density, or nearly so, of the portions of the product below. That is, the excess height of the core and the dies is such that, when the upper portions are compressed vertically from the condition shown in FIGS. 7 and 10 to the position shown in FIGS. 8 and 11, the upper portion of the product is compressed the same as the lower portion thereof.

After the product has been formed, the vertical 31 and horizontal 23 pressing dies are retracted and the hydraulic unit 36 is operated to cause the ejector rods 38 to push upwardly on the pallet frame 34 so as to raise the product above the dies, as indicated in FIG. 1. The product with its pallet is removed and then cured.

The grating permits excess mixture, if any, to fall downward through the grating by gravity or an air jet in preparation to receiving another pallet to repeat the pressing operation.

Reference is now directed to FIGS. 12 and 13. Should it be desired to provide a knockout web in a side or end wall, the forming die 23 is provided with a channel 39 in its underside which accommodates a knockout die plunger 40. The channel 39 is disposed parallel to the axis of travel of the forming die 23; that is, at a forty-five degree relation to the die face 24 or 25. The plunger 40 terminates in a die face 41 which is parallel to the die face 24 or 25 and, when extended, confronts a pad or boss 42 formed on the core 19.

A shaft 43 is attached to the plunger and protrudes from the backside of the die block and terminates in a head 44 which limits outward movement of the die face 41. A strong coil spring 45 normally holds the die face 41 in its extended position.

Alternatively, as shown in FIG. 14, the rearwardly protruding end of the shaft 43 may be provided with a piston which is received in a cylinder 46 so that the die face 41 may be extended or retracted hydraulically.

The web forming die operates as follows:

The die face 41 is initially in an extended position to limit the amount of cementitious material received between the die face 41 and boss 42. As the cementitious material is compressed, the die face retracts a distance depending upon the strength of the spring. The spring force may be such that the cementitious material within the web is less compressed than the remaining portions of the meter box and, therefore, weaker so that the web may be readily knocked out.

If the construction shown in FIG. 14 is used, the hydraulic force is controlled by conventional means, not shown.

While particular embodiments of this invention have been shown and described, it is not intended to limit the same to the details of the constructions set forth, but instead, the invention embraces such changes, modifications and equivalents of the various parts and their relationships as come within the purview of the appended claims.

I claim:

1. A machine for producing a product by press forming a compressible cementitious mixture, comprising:

(a) a central core having relatively fixed essentially flat angularly related sides facing in opposite directions;

(b) a pair of opposed complementary dies having relatively fixed essentially fiat angularly related die faces disposed essentially parallel to corresponding sides of the central core;

() and means for moving the dies in opposition along a common axis between an outer position for reception of a predetermined quantity of compressible cementitious mixture between the die faces and the corresponding sides of the core, and an inner position thereby to compress the mixture between the die faces and the core;

(d) the die faces and core sides forming equal angles with the axis of movement of the dies, whereby the density of the product formed by the compresed mixture is essentially equal to all sides.

2. A machine, as defined in claim 1, wherein:

(a) the central core and confronting surfaces of the dies including upper and lower ends and the confronting surfaces of the dies, when closed, being passed from the core a greater distance at one of their confronting ends than at their other confronting ends;

(b) and a die ring is dimensioned to enter between the core and die faces to effect compression of the mixture in the region of greater spacing to essentially the same density as the mixture between other spaced portions of the core and the die faces.

3. A machine, as defined in claim 1, wherein:

(a) a housing supports the core and the opposed dies for horizontal movement of the dies;

(b) a grating surrounds the base of the core for discharge of excess mixture;

(c) and a pallet ring is removably received on the grating to support the resulting product formed by the core and confronting dies for removal from the core.

4. A machine, as defined in claim 3, wherein:

(a) the central core and confronting surfaces of the dies have greater spacing at their top portions;

(b) a vertically movable die ring is supported above the core for vertical movement into the space between the upper portions of the core and die surfaces after initial compression of the mixture therein, thereby to effect further compression of the mixture in a vertical direction to increase its density to that of the mixture below.

5. A machine for producing a product by press forming a compressible cementitious mixture, comprising:

(a) a central core;

(b) a pair of opposed complementary dies having die faces confronting opposite sides of the core;

(0) means for moving the dies in opposition along a common axis between an outer position for reception of a compressible cementitious mixture between the die faces and the core, and an inner position thereby to compress the mixture between the die faces and the core;

(d) a web forming die having a fixed die element and confronting a movable die element protruding into the space between the core to receive a lesser quantity of cementitious material therebetween;

(e) and yieldable means backing the movable die element thereby to apply a predetermined compression force on the cementitious material therebetween independently of the force applied to the remaining cementitious material.

References Cited UNITED STATES PATENTS 3,162,895 12/1964 Busch 18-5 R 3,090,093 5/1963 Long 25-45 3,058,153 10/1962 Busch 18DIG. 58 3,484,510 12/1969 Corazza 18-5 P X 3,566,442 3/1971 Hakala 18-5 P X H. A. KILBY, 1a., Primary Examiner US. Cl. X.R.

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